Pipes still banging

29 Oct 2007
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United Kingdom
I have a baxi solo 2 PF. The CH and HW are working, the pump and tank star are working. I have CH and HW. Ocasionaly the boiler goes on over heat setting. The boiler is turned down to No.2 setting. The tank stat is turned down to 50 and the pump is turned up to No.3 setting since No.2 setting was just as bad, i thought the pomp would pump the water thus pushing the water through faster and sorting the problem. When the CH heats up, the pipes bang, generally as the boiler goes off, but sometimes the boiler goes to the overheat setting. All the rads have been blead and the tank valve as well so as far as i can see there is no air in the system.
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Does the pump carry on running for about ten mins after clock/stats stop demanding heat
Yes, the pump does as it`s told when it`s told. It`s just when the water gets so hot, it heads for the loft and the pipes let me know about it. It`s frustrating since it was fine 2 days ago, but then when i turned the CH off for 2 days and turned it back on again, this started happening again. I just can`t see why ( if i could i wouldn`t be here would i, lol )
Couple of things it could be . Intermitent fault on boiler stat not shutting down everytime and allowing boiler to get far too hot and Check that the actual gas valve is closing down everytime it maybe sticking on intermitently causing boiler to over heat also
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When the boiler turns off, everything goes off as it should. Unless something on the boiler that i can`t see without opening it up is turned up too high, because all of the setting everywhere around the house that i can see, i have turned down almost as low as i can to try and sort the problem.

The sensor is the boiler thermostat fitted in top pipe on right hand side .

Part nuimber 73 in the parts list i would also change part 71a the potentiometer and leads at same time as they are both connected
Ok. pulled the boiler to bits, now i can`t put it back together again....bad joke, sorry. I had a good look round the boiler and the aincent looking circuit board and nothink looks to be burnt out. checked the sensor and that looked ok as did the overheat stat. Now turned everything on and seeing what happens. brb
the HW when running on it`s own does not overheat, so i can`t see why the CH should. Dont they both use the same sensors ?
The first few times when starting the boiler, it does not overheat. So everything must be working or it would overheat first time wouldn`t it ?
As you originally said it does it occasionally you will just have to wait and see.. Intermittent faults are a pain to diagnos till you actually catch it doing the fault
well it didn`t overheat this time, but i could hear the water boiling in the pipes and venting into the loft, but it`s only a matter of time. Does it really matter what setting i have the pump on. 1. 2. or 3 ?

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